The present invention relates to a gymnastic bicycle including a device to transmit vibrations generated by the effect of pedaling to the body of the user and a mechanism for regulating the physical effort necessary for practicing the exercise of rowing.
As is known in a gymnastic or static bicycle, apart from the conventional pedaling exercise similar to that of a conventional movable bicycle, there is the possibility of practicing the exercise of rowing through the alternating oscillation of the handlebars, and also of supplying a vibratory movement to the body of the user, at certain positions of the bicycle elements and when pedaling.
According to the invention, the vibrator mechanism includes a lever having one end connected permanently to a hub which defines an articulation between the bottom end of a tube or stem of the handlebars and the chassis or static structure of the bicycle, such hub thus allowing a rowing exercise. The other end of the lever is provided with a roller adapted to contact a rotating polygonal surface, which rotation is achieved by pedaling of the bicycle. When the roller is in contact with the polygonal surface, a reciprocal pivoting movement is imparted to the lever, and this is converted into a vibration transmitted to the handlebars and from here to the body of the user.
According to the invention, the polygonal surface against which the lever roller makes contact forms part or is closely linked to an inertia flywheel which forms a power regulator accumulator for pedaling and contact and/or separation of the roller with respect to the polygonal surface is achieved by regulating the position of a control knob and thereby a rod or shank having at a free end thereof two axially spaced abutting surfaces for contacting a plate fixed to the end of the lever adjacent the hub. Such two abutting surfaces define two positions for the lever, one with the roller abutting the polygonal surface and the other with the roller spaced therefrom.
Thus, there is formed a vibrator for a gymnastic bicycle having the advantages inherent in an inertia flywheel with which this type of bicycle is equipped, compared with a conventional vibrator wherein the polygonal surface is made on a gooseneck linked to the pedaling axis of the bicycle.
In accordance with a preferred embodiment, the polygonal surface against which the lever roller makes contact is located in an internal periphery of a rim of the inertia flywheel.
In a second embodiment, the polygonal surface is formed on a body or pin linked to the inertia flywheel shaft.
As mentioned hereinabove, the invention provides a device for regulating the physical effort required to perform a rowing exercise. Such regulating device includes a hub defining two internal equal frusto-conical surfaces having confronting smaller bases. Such frusto-conical surfaces are contacted by complementary shaped outer surfaces of respective bodies. Each body has a castellated end section keyed to the bicycle chassis, thereby allowing axial displacement of the bodies relative to the hub to thus regulate the degree of effort required to rotate the hub. The hub is fixed to the lower end of the tube or stem of the handlebars, such that the handlebar assembly can pivot within the longitudinal plane of the bicycle, through the physical effort of the user on pulling the handlebars towards him.
The bodies are connected to each other by means of a bolt which extends axially through the bodies, the bolt being provided at one of its ends with a hand-driven knob which has a bushing extending into an axial recess in the outer end of the respective body. The other body has formed in the outer end thereof a recess having a polygonal section and receiving a correspondingly shaped nut into which is threaded the other end of the bolt. Rotation of the bolt by the knob makes the two bodies move together or apart, and in this way it is possible to regulate the effort necessary to rotate the hub relative to the bodies.
The polygonal recess which holds the tightening nut is deeper than the thickness of the nut, and an expansion spring is interposed between the nut and the bottom of the recess, thus urging the respective body away from the nut and against the respective frusto-conical surface of the hub. Adjacent smaller ends of both bodies have respective recesses receiving another expansion spring tending to separate the bodies.
The regulator device of the invention is simplified considerably, both from the structural point of view and from the functional viewpoint, compared with conventional devices of this type. Thus, in accordance with conventional engineering regulation of this type is achieved by the use of a pinion joined to the middle area of a bolt joining two frusto-conical bodies. Such pinion cooperates with a pawl provided radially on the hub and retractable against the tension of a spring. A manual control knob is provided radially and externally of the hub.
In accordance with the invention, the internal pinion, the spring and the external radial control knob are eliminated, thus providing a more economical device and one with which the risks of failure of complex elements is avoided.